JP2533704B2 - Radiant tube burner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant tube burner applied as a heat source for an atmosphere heat treatment furnace, a metal melting furnace and the like.

[0002]

2. Description of the Related Art As a conventional technique, for example, Japanese Patent Laid-Open No. 63-6 is available.
There is a publication 5217. This publication discloses a tube burner in which a heat-resistant particle group contained in an outer tube is vertically moved by combustion gas.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to make the temperature distribution of the heat transfer surface uniform in the vertical and circumferential directions in a radiant tube burner using a heat resistant particle group as a heating medium. is there.

[0004]

The radiant tube burner of the present invention is a vertically installed outer tube having a bottomed cylindrical shape, in which heat-resistant particles are enclosed, and the outer tube is concentrically formed. Around the inserted substantially cylindrical inner tube, an outer passage is formed that causes the particle groups blown up by the combustion gas flow that flows downward and flows upward from above to flow upward together with the combustion gas. the inner forms the inner passage for introducing said outer passage in said particles flowing out of the allowed drop flow into the lower end of the outer passage, the bottom surface of the outer tube, the combustion gas collides with the this bottom this bottom Of the central axis of
It is evenly guided around the entire circumference and flows back in a U-turn shape.
Curved configuration equivalent concavely curved over the entire periphery so that
In the configuration, a dispersion guide surface is formed in an annular recess around the central axis of the bottom surface .

[0005]

[Operation] Radiant tube bar having the above structure
In the outer tube, combustion gas descends and flows inside the outer tube.
Combustion gas is dispersed on the guide surface when it flows back at the lower end of the
Collision and the entire circumference around its center due to this distributed guiding surface
Is evenly guided to flow back in a U-turn shape. The heat-resistant particle group enclosed in the outer tube is dispersion-induced.
It is blown up by the combustion gas flow that collides with the surface and flows back, and ascends with the combustion gas flow in the outer passage, and then is introduced to the upper end in the inner passage inside the inner tube.
As a result, the combustion gas flow flowing back inside the inner passage is introduced again to the lower end in the outer passage, and is repeatedly circulated in the outer passage and the inner passage.

[0006]

Since the present invention is constructed as described above, the combustion gas is made to collide with the dispersion guide surface in a uniform state over the entire circumference thereof so as to be evenly distributed in the circumferential direction of the dispersion guide surface. The combustion gas can be made to flow back and flow can be made uniform and stable in the circumferential direction and the vertical direction of the outer passage while the combustion gas is flowing upward in the outer passage. Of the outer tube can be stabilized throughout the outer passage, and the temperature distribution in the circumferential and vertical directions of the heat transfer surface of the outer tube is made uniform, and in particular, the temperature distribution in the lower part of the heat transfer surface is made uniform. can do.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to the drawings. In a radiant tube burner B that serves as a heat source for an atmosphere heat treatment furnace, a metal melting furnace, etc., an outer tube 2 formed of a stainless material or a ceramic material in a cylindrical shape with a bottom has a disc shape that is fastened to a mounting surface such as a furnace wall. It is installed vertically in a state of being inserted and fixed in the central portion of the flange 1.

Of the outer side surface of the outer tube 2, a heat transfer surface 2a is formed below the flange 1, and the upper end of the outer tube 2 is closed by a cover plate 3.
An exhaust gas pipe 5 is connected to the discharge port 4 opened near the upper end of the.

An upper portion of the width of the outer tube 2 has a large number of meshes for allowing gas to flow therethrough, and a peripheral edge portion is gripped by the flange 1 and a diffusion prevention net 18 disposed near the upper end of the heat transfer surface 2a is provided. It is installed horizontally.

On the bottom surface of the outer tube 2, there is formed a protruding portion 2b having a sharp conical shape with a sharp center , and the thickness of which gradually decreases outward . the bottom surface of the outer tube 2, the bay into equal concave curved surface over the entire circumference
In a bent form, an annular recess is provided around the central axis 22 of this bottom surface.
The dispersed guide surface 21 is formed.

The outer tube 2 is formed of a stainless material or a ceramic material in a substantially cylindrical shape, and the upper end edge 6a is disposed below the anti-scattering net 18 and the lower end edge 6b is disposed above the dispersion guide surface 21. Shaped inner tubes 6 are concentrically inserted with a gap.

An outer passage 7 is formed around the inner tube 6, and a funnel-shaped tapered portion 6c having a diameter gradually increasing upward is formed near the upper end of the inner tube.

The inner tube 6 is made of a stainless material or a ceramic material and is formed into a substantially cylindrical shape.
A combustion tube 8 inserted near the upper end of the inner passage is concentrically inserted, and between the combustion tube 8 and the inner tube 6, an inner passage 6 is provided inside the outer passage 7 with an inner tube 6 interposed therebetween. 9 is formed.

A divergent taper portion 8a having a diameter gradually increasing downward is formed near the lower end of the combustion tube 8, and between the lower end edge of the taper portion 8a and the dispersion guide surface 21 of the outer tube 2. Has a first communication port 10 that connects the inside of the combustion tube 8 and the outer passage 7, and connects the outer passage 7 and the inner passage 9 between the tapered portion 8a and the lower end edge 6b of the inner tube 6. The second communication port 11 is formed.

An inlet port 19 through which secondary air is introduced into the combustion tube 8 is opened near the upper end of the combustion tube 8.
A secondary air supply conduit 20 is connected to the inflow port 19. An outlet 8b through which combustion gas flows out is opened at the lower end of the combustion tube 8.

A gas pipe 12 connected to a gas supply pipe 13 for supplying a mixed gas in which gas fuel and primary air are premixed is inserted in the upper portion of the combustion tube 8 with a gap therebetween. The ignition plug 14 is inserted through the central portion.

A gas pipe 1 is provided in the upper part of the combustion tube 8.
A burner nozzle 15 connected to the tip of 2 is inserted, and a secondary air flow passage 16 for supplying secondary air around the burner nozzle 15 is formed between the combustion tube 8 and the gas pipe 12.

The secondary air is blown through the secondary air flow path 16.
See write feed to around Nanozuru 15, when burning the admission gases was fed to the burner nozzle 15, the combustion gases or outlet 8b of the combustion tube 8 descends flowing in the combustion tube 8
Outflow. The combustion gas flowing out from the outflow port 8b collides with the dispersion guide surface 21 and the dispersion guide surface 21 causes the central axis 22
Is uniformly guided around the entire circumference of the dispersion guide surface 21 and is evenly distributed in the circumferential direction of the dispersion guide surface 21 so as to flow back in a U-turn shape and flow outside.
It flows into the lower end of the side passage 7, flows upward in the outer passage 7, and is discharged from the discharge port 4.

A heat-resistant particle group 17 such as alumina particles, which can be blown up by a combustion gas flow that flows out of the outlet 8b of the combustion tube 8 and flows back into the outer passage 7, is enclosed in the outer tube 2, The particle group 17 is deposited in the lower portion of the outer tube 2 before combustion.

The particle group 17 is the outlet 8b of the combustion tube 8.
Is blown up while being heated by the combustion gas flow flowing back from the outer passage 7 and is introduced into the outer passage 7 and flows upward in the outer passage 7 together with the combustion gas in a diffused state to flow out from the upper end of the outer passage 7, It is introduced into the upper end of the inner passage 9 by hitting the sprinkling net 18, drops and flows in the inner passage 9 by its own weight, and flows from the lower end of the inner passage 9 to the second communication port 1
After passing through No. 1, it again flows into the lower end of the outer passage 7 and repeatedly circulates in the outer passage 7 and the inner passage 9.

Next, the operation and effect of the above embodiment will be described. In this example, a heat-resistant particle group 17 is enclosed in a bottomed cylindrical outer tube 2 that is vertically installed, and is surrounded by a substantially cylindrical inner tube 6 that is concentrically inserted into the outer tube 2. An outer passage 7 is formed in the inner tube 6 to allow the particle group 17 blown up by the combustion gas flow that flows downward from above and returns upward to flow upward together with the combustion gas.
The particles 17 flowing out from the inside are made to fall and flow to the outside passage 7
Forming an inner passage 9 introduced to the lower end of the outer tube
The combustion gas that collided with this bottom surface of the bottom surface of 2
A uniform U-turn is formed around the central axis 22.
A uniform concave curved surface over the entire circumference so as to aliasing flow
It has a curved shape and is annularly concave around the central axis 22 of the bottom surface.
The provided dispersion guide surface 21 is formed.

Therefore, the combustion gas flowing out from the outlet 8b at the lower end of the combustion tube 8 is made to collide with the dispersion guide surface 21 in a uniform state over the entire circumference thereof, so that the inside of the dispersion guide surface 21 is covered.
No combustion gas is distributed evenly around the core.
Can be physical rather than folding flow, combustion gases it is possible to uniformly and stabilized in the circumferential direction and the vertical direction of the outer passage 7 a fluidized state when the rising flow of the outer passageway 7, the particles 17 It is possible to stabilize the flow state at the time of rising flow over the entire inside of the outer passage 7, uniformize the temperature distribution in the circumferential direction and the vertical direction of the heat transfer surface 2a of the outer tube 2, and particularly to the heat transfer surface 2a.
The temperature distribution in the circumferential direction of the lower part of the can be made uniform.

Further, since the mixed gas in which the gas fuel and the primary air are premixed is supplied to the burner nozzle 15 and burned, the mixed state of the gas fuel and the air is made uniform, the ignitability is improved, and stable combustion is achieved. The state can be continued, the carbon monoxide concentration can be reduced, and the stable combustion range can be expanded.

Next, the second embodiment shown in FIG. 3 will be described. In this embodiment, the length of the combustion tube 8A is shortened to form the inner passage 9A inside the inner tube 6, and the lower end of the combustion tube 8A is The structure is the same as that of the first embodiment except that the combustion gas is inserted into the upper end of the inner tube 6 and flows downward together with the particle group 17 in the inner passage 9A and collides with the dispersion guide surface 21. ing.

Since the operation and effect of the second embodiment are almost the same as those of the first embodiment, the description thereof will be omitted.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a radiant tube burner showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a vertical sectional view of a radiant tube burner of a second embodiment.

[Explanation of symbols]

 2 Outer tube 6 Inner tube 7 Outer passage 9,9A Inner passage 17 Particle group 21 Dispersion guide surface B Radiant tube burner

Claims (1)

(57) [Claims] 1. A heat-resistant particle group is enclosed in a bottomed cylindrical outer tube that is vertically installed, and is surrounded by a substantially cylindrical inner tube that is concentrically inserted into the outer tube. Is an outer passage that causes the particles that are blown up by the combustion gas flow that flows downward from above and returns upward to flow upward together with the combustion gas, and inside the inner tube, the particles that have flowed out of the outside passage. is dropped fluidized groups forms the inner passage to be introduced into the lower end of the outer passage, the bottom surface of the outer tube, the combustion gas collides with the this bottom of the center axis of the bottom surface
It is evenly guided around the entire circumference and flows back in a U-turn shape.
Curved configuration equivalent concavely curved over the entire periphery so that
1. A radiant tube burner characterized in that a dispersion guide surface is formed in an annular shape around the central axis of the bottom surface .